This invention relates to semi-synthetic cephalosporin antibiotics. In particular, it relates to cephalosporin antibiotic compounds represented by the general formula 1 ##STR2## wherein R is a 5- or 6-membered heterocycle; R.sub.1 is an aralkyl, aryloxyalkyl, or arylthioalkyl group; R.sub.2 is a 1,2,4-triazine thio substituent; and M is hydrogen, a salt-forming cation, or a biologically labile ester group.
Cephalosporin antibiotics having an oximino group forming part of the 7-position side chain substituent are known. For example, U.S. Pat. No. 3,974,153 describes the methoximino cephalosporin known as cefuroxime; U.S. Pat. No. 4,098,888 describes oximino 3-heterocyclic thio cephalosporins; U.S. Pat. No. 4,152,432 describes the methoximino substituted cephalosporanic acid known as cefotaxime; U.S. Pat. No. 4,327,210 discloses the 3-thiazine thio substituted methoximino cephalosporin known as ceftriaxone; U.S. Pat. No. 4,427,674 describes 3-unsubstituted methoximino cephalosporins such as ceftizoxime. The oximino substituted cephalosporin antibiotics exhibit high antibacterial potency.